fix(codex): apply global service tiers to combo request bodies

src/lib/providers/codexFastTier.ts

@@ -130,8 +130,8 @@ export interface ApplyCodexGlobalFastServiceTierOptions {
    */
   model?: string | null;
   /**
-   * Outbound request body. Per-request body.service_tier is left untouched if
-   * already set.
+   * Outbound request body. A valid per-request body.service_tier is left untouched
+   * when already set.
    */
   body?: Record<string, unknown> | null;
 }
@@ -188,12 +188,11 @@ export function applyCodexGlobalFastServiceTier<T extends JsonRecord | null | un
     } as T;
   }
 
-  if (resolved.tier === "flex") {
-    // Write the wire value directly to the outbound body when possible. The executor
-    // also accepts requestDefaults.serviceTier = "flex" for downstream accounting.
-    if (body && typeof body === "object" && !Array.isArray(body)) {
-      (body as JsonRecord).service_tier = "flex";
-    }
+  if (body && typeof body === "object" && !Array.isArray(body)) {
+    // Write the wire value directly to the outbound body when possible, so combo
+    // request previews and logs show the same effective tier that the executor sends.
+    // The executor also accepts requestDefaults.serviceTier for downstream accounting.
+    (body as JsonRecord).service_tier = resolved.tier;
   }
 
   // Intentional precedence: body service_tier > global mode > connection defaults.

tests/integration/chat-pipeline.test.ts

@@ -606,6 +606,47 @@ test("chat pipeline persists Codex responses cache and reasoning tokens to call
   assert.equal(callLog.tokens.reasoning, 13);
 });
 
+test("chat pipeline applies global Codex priority service tier inside combos", async () => {
+  await seedConnection("codex", { apiKey: "sk-codex-combo-priority" });
+  await settingsDb.updateSettings({
+    codexServiceTier: { enabled: true, tier: "priority" },
+  });
+  await combosDb.createCombo({
+    name: "codex-priority-combo",
+    strategy: "priority",
+    config: { maxRetries: 0, retryDelayMs: 0 },
+    models: ["codex/gpt-5.5"],
+  });
+  const fetchCalls = [];
+
+  globalThis.fetch = async (url, init: RequestInit = {}) => {
+    fetchCalls.push({
+      url: String(url),
+      headers: toPlainHeaders(init.headers),
+      body: init.body ? JSON.parse(String(init.body)) : null,
+    });
+    return buildOpenAIResponsesSSE({ text: "combo priority ok", model: "gpt-5.5" });
+  };
+
+  const response = await handleChat(
+    buildRequest({
+      body: {
+        model: "codex-priority-combo",
+        stream: false,
+        messages: [{ role: "user", content: "Use Codex combo priority" }],
+      },
+    })
+  );
+
+  const json = (await response.json()) as any;
+  assert.equal(response.status, 200);
+  assert.equal(fetchCalls.length, 1);
+  assert.match(fetchCalls[0].url, /\/responses$/);
+  assert.equal(fetchCalls[0].headers.Authorization, "Bearer sk-codex-combo-priority");
+  assert.equal(fetchCalls[0].body.service_tier, "priority");
+  assert.equal(json.choices[0].message.content, "combo priority ok");
+});
+
 test("chat pipeline applies Codex CLI fingerprint to OAuth responses requests", async () => {
   setCliCompatProviders(["codex"]);
   await seedConnection("codex", {
@@ -950,12 +991,7 @@ test("chat pipeline sends Gemini CLI OAuth requests with native Cloud Code trans
   assert.equal(generateCall.body.requestId, undefined);
   assert.equal(generateCall.body.user_prompt_id, generateCall.body.request.session_id);
   const keys = Object.keys(generateCall.body).slice(0, 4);
-  assert.deepEqual(keys.sort(), [
-    "model",
-    "project",
-    "request",
-    "user_prompt_id",
-  ]);
+  assert.deepEqual(keys.sort(), ["model", "project", "request", "user_prompt_id"]);
   assert.equal(generateCall.body.request.sessionId, undefined);
   assert.match(generateCall.body.request.session_id, /^[0-9a-f-]{36}$/i);
   assert.equal(generateCall.body.request.contents.at(-1).parts[0].text, "Hello Gemini CLI");

tests/unit/codex-fast-tier.test.ts

@@ -106,15 +106,17 @@ test("Codex global service tier injects selected mode and can override connectio
 });
 
 test("Codex global service tier matches provider-prefixed combo model ids", () => {
+  const body: Record<string, unknown> = {};
   assert.deepEqual(
     applyCodexGlobalFastServiceTier(
       "codex",
       { providerSpecificData: {} },
       { codexServiceTier: { enabled: true, tier: "priority" } },
-      { model: "codex/gpt-5.5" }
+      { model: "codex/gpt-5.5", body }
     ),
     { providerSpecificData: { requestDefaults: { serviceTier: "priority" } } }
   );
+  assert.equal(body.service_tier, "priority");
 
   const unsupported = { providerSpecificData: {} };
   assert.equal(
@@ -155,7 +157,7 @@ test("Codex global service tier only short-circuits on valid body service_tier",
   assert.deepEqual(injected, {
     providerSpecificData: { requestDefaults: { serviceTier: "priority" } },
   });
-  assert.equal(invalidBody.service_tier, "invalid");
+  assert.equal(invalidBody.service_tier, "priority");
 
   const validBody: Record<string, unknown> = { service_tier: " Flex " };
   const unchanged = { providerSpecificData: {} };